Polio

Why in News?

With the possibility of a new Covid-19 variant triggering a new surge in cases, the Centre has asked the states to send sewage samples to all sentinel sites that currently perform surveillance of Poliovirus.

  • Sentinel surveillance is the “monitoring of rate of occurrence of specific diseases or conditions through a voluntary network of doctors, laboratories and public health departments with a view to evaluate  the stability or change in health levels of a population”.

What is Polio?

  • Polio is a crippling and potentially fatal viral infectious disease that affects the nervous system.
  • There are 03 individual and immunologically distinct wild poliovirus strains-
  • Wild Poliovirus type 1 (WPV1).
  • Wild Poliovirus type 2 (WPV2).
  • Wild Poliovirus type 3 (WPV3).
  • Symptomatically, all three strains are same, in that they cause irremediable paralysis or even death.
  • Although, there are genetic and virological differences which make these three strains separate viruses which must each be exterminated individually.
  • Spread- The virus is transmitted by human to human mainly through the faecal-oral route or, less frequently, by a common vehicle (forinstance, through contaminated water or food).
  • It mostly affects children under 05 years of age. The virus multiplies in the intestine, from where it can occupy the nervous system and can cause paralysis.
  • Symptoms- Most people with polio do not feel sick. Some people have only minor symptoms like fever, tiredness, nausea, headache, pain in the arms and legs, etc.
  • Polio infection causes permanent loss of muscle function (paralysis) in rare cases.
  • Polio can be deadly if the muscles used for breathing are paralysed or if there is an infection of the brain.
  • Prevention and Cure- There is no cure of polio but it can be prevented through Immunisation.
  • Vaccines-
  • Oral Polio Vaccine (OPV)- It is provided orally as a birth dose for institutional deliveries, then primary 03 doses at 06, 10 and 14 weeks and one booster dose at 16-24 months of age.
  • Injectable Polio Vaccine (IPV)- It is introduced as an additional dose together with the third dose of DPT (Diphtheria, Pertussis and Tetanus) under the Universal Immunisation Programme (UIP).
  • Recent Outbreaks- In 2019, polio outbreaks were registered in the Philippines, Malaysia, Ghana, Myanmar, Cameroon, China, Indonesia and Iran, which were mostly vaccine-derived in which a rare strain of the virus genetically mutated from the strain in the vaccine.
  • As per the WHO (World Health Organisation), if the oral vaccine-virus is excreted and permitted to circulate in an unimmunised or under-immunised population for at least 12 months, it can mutate to cause infections.
  • India & Polio- In 2014, India received polio free certification by the WHO, after 03 years of zero cases.
  • This achievement has been stimulated by the successful Pulse Polio Campaign in which all children were administered polio drops.
  • The last case of wild poliovirus in the country was noticed on 13th January 2011.

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